ELECTROCATALYSIS FOR OXYGEN ELECTRODES IN FUEL-CELLS AND WATER ELECTROLYZERS FOR SPACE APPLICATIONS

The lead ruthenate pyrochlore Pb2Ru2O6,5, in both high- and low-area forms, has been characterized using thermogravimetric analysis, X-ray photo-electron spectroscopy, X-ray diffraction, cyclic voltammetry, and O2 reduction and generation kinetic-mechanistic studies. Mechanisms are proposed. Compounds in which part of the Ru is substituted with Ir have also been prepared. They exhibit somewhat better performance for O2 reduction in porous, gas-fed electrodes than the unsubstituted compound. The anodic corrosion resistance of pyrochlore-based porous electrodes was improved by using two different anionically conducting polymer overlayers, which slow down the diffusion of ruthenate and plumbate out of the electrode The O2 generation performance was improved with both types of electrodes. With a hydrogel overlayer, the O2 reduction performance was also improved. © 1990.